Video: HP calls for on-chip optics

SAN JOSE, Calif.  Multicore processors will need to adopt optical interconnects over the next decade to deliver the bandwidth and programmability the computer industry needs, said a researcher from Hewlett-Packard Co.

"We have to re-define what the IC looks like," said Ray Beausoleil, a researcher in the quantum optics group at HP Labs in a keynote address at Photonics West here.

"Over the next ten years dense wavelength division multiplexing [DWDM] and optical interconnects are inevitable at distances of a few millimeters and above," he added.

The shift from copper links is needed to serve computer processors that could scale to 256-core CPUs projected to arrive by 2017, delivering as much as 10 Teraflops of performance. Such chips will need as much as 20 TFlops bi-directional bandwidth to support a relatively flat programming model.

Without using optical links and DWDM signaling, such bandwidth could require more than 16,000 wires and 256 waveguides. Beausoleil talked about the problem and some of the challenges solving it in a short interview after the keynote.

"I think we have identified all the problems and have candidate solutions for all of them, but we are far from certain those candidate solutions will work," he said in an interview.

For its part, HP Labs has developed prototype ring resonators as small as three microns in diameter that could act as building blocks for an on-chip optical crossbar. The resonators could detect, modulate and switch optical signals, he said.

But fabricating these rings and placing quantities of them on chips with nanometer-level precision will be a top challenge. Engineers also face power consumption challenges because driving the interconnects could require as much as 50W of power.

"It looks like we have ten years to do this, but decisions on the technology have to be made many years in advance," he said, challenging researchers in a packed auditorium here to begin work on the many underlying problems.